Jeff Hafley's coaching career began sooner than he expected.

Three surgeries in four seasons as an undersized receiver at Siena College prompted the change.

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Hafley was in his office at the Woody Hayes Athletic Center recently when he recalled the wounds. He tugged his shoulder. He'd had arthroscopic surgery while he was an underclassman. He rubbed his legs. Both were ravaged by compartment syndrome, a muscle and nerve condition that threatened to end his playing career.

“My whole college career,” Hafley said, “was basically rehab, comeback.”

One benefit emerged. His coaches at Siena, in upstate New York, discovered a sharp mind. When injuries kept him off the field, Hafley went to the coaching booth. He helped the defensive staff identify opposing receivers' routes. His input carried enough weight that he traveled for road games.

“That kind of made me say, 'This is what I want to do,'” Hafley said.

Over the next two decades, Hafley ascended the coaching ladder, including stops in the NFL, before joining the Buckeyes this year. As co-defensive coordinator, he is tasked with rehabilitating a unit that set a school record for points allowed last season.

It has been a long-shot rise for the 40-year-old.

Hafley’s coaching career began at Worcester Polytechnic Institute, a Division III school in Massachusetts, before moving to Albany, a Football Championship Subdivision program. In his first season as running backs coach at WPI, he earned so little that he scraped jars of peanut butter for meals.

“You get full on it fast,” Hafley said.

A big break came later. After five seasons, he joined Pittsburgh as a graduate assistant in 2006.

Hafley had caught the attention of coaches while visiting their clinics.

“He’s a junkie when it comes to ball,” said UCLA defensive backs coach Paul Rhoads, who was then defensive coordinator at Pitt. “He wanted to talk as much ball as he could, whether it was a particular scheme that we talked about or a sequence of drills that I had covered. He was a sponge.”

His eagerness continued when he joined the program. Hafley met with Panthers defensive backs in his office in the early morning hours, sometimes more than an hour before the rest of the team gathered. It helped to have Darrelle Revis, a future NFL All-Pro cornerback, among the group.

During his initial seasons as a graduate assistant, Hafley rarely left the team’s facility. He slept six nights a week on an air mattress in his office.

“I just wanted to do everything I could,” Hafley said. “I felt like if I did that and put in all the time and all the work, at the end of the day, if there was a position for me, I had hoped that they'd hire me, and if there wasn't, then I could be OK with it.”

While Hafley had reached a bigger program, he also left a stable setup at Albany, where he had been promoted as secondary coach and recruiting coordinator. The Great Danes were successful under Bob Ford, who finished his career as one of the winningest FCS coaches.

The graduate assistant position at Pittsburgh involved a pay cut and no guarantee of a full-time role after the first two seasons. He risked returning to square one.

“Most guys get into a comfort zone,” said Dave Wannstedt, then the Panthers’ coach. “They're coaching some place and they're winning some games and they're putting a paycheck into their pocket. The easy thing is to stay. The tough thing is to make a career decision.”

Hafley referred to the move as a calculated risk, one he and friends reflected on from time to time.

“That risk I took really catapulted everything,” Hafley said.

Wannstedt later hired Hafley as his secondary coach. When Wannstedt was fired in 2010, he recommended Hafley to Rutgers coach Greg Schiano. It became a valuable connection. Hafley headed to the NFL after one season with the Scarlet Knights, following Schiano, who was named coach of the Tampa Bay Buccaneers.

Hafley remained in the professional ranks as an assistant for seven seasons until late last year. Seated with his wife, Gina, at a fast-food restaurant in Los Gatos, California, Hafley noticed his phone buzzing.

On the other end was Ryan Day, the newly named Ohio State coach. The two spent 2016 together on the San Francisco 49ers staff.

Hafley had turned down other defensive coordinator positions in recent seasons, hoping to land such a role in the NFL. He thought he was close, a hunch that proved correct in February when the Cincinnati Bengals showed interest in him.

But Hafley ultimately followed Day and was paired with Greg Mattison, the former Michigan defensive line coach, as co-coordinator. Hafley also serves as secondary coach, overseeing a unit that struggled last season.

Mattison raved about his new partner midway through preseason camp.

“He's as good a secondary coach as I've ever seen,” he said.

Most people at Ohio State bring up Hafley’s NFL background. He coached some of the league’s top defensive backs and studied under sharp coordinators. But some of his best traits took form early in his coaching career.

As a graduate assistant at Pitt, he learned from Rhoads that teaching fundamentals was as important as installing complex schemes. He appeared personable while first recruiting high school players, often in his native New Jersey.

“He comes across as a total sincere human being,” said Ford, the former Albany coach, “does all the things you'd like to see, leans across the table, listens intently, eye-to-eye contact, all of those things. You say everyone does that. Eh. It's been a lost art.”

Hafley's work in helping overhaul the Buckeyes defense will not begin to come into clear view until the season begins Saturday against Florida Atlantic. But his imprint on the program has been months in the making, beginning with his earnestness in the locker room.

In his first week at Ohio State in January, he persuaded starting cornerback Damon Arnette to return for his senior season.

“I didn't sell him anything,” Hafley said. “I didn't promise him anything. I just told him the truth.”

Then he dashed to the next step.

jkaufman@dispatch.com

@joeyrkaufman